Don't worry about it. The human mind is good at imagining all sorts of stuff that is sometimes worse than the reality.
If she DID mean you to see it, how do you know that wasn't to test the water and see if you still fancy her? (i.e, ellicit a response out of you).
Until she actually tells you, 'I have OM' I wouldn't let your imagination run riot, it will only serve to torture you and not help you.
You stated she said 'what time is it?' when you tried to leave. She was stalling because she enjoys your company. Try to focus on the positives instead of negatives you don't even know exist.
Your son told you to have OW because he loves you and wants to see you happy and thinks you will be with another partner. My dd1 told me to marry somebody for the same reason, they say it because they care. Don't take it too seriously. It's very early days yet for you and I think you are killing yourself with expectations and fears.
Just try to go with the flow and enjoy more times like this with W and S5. You are showing her how you can be supportive and she has responded positively to this.
